This invention relates generally to skin whitening or skin lightening compositions for cosmetic use.
The present invention relates to a skin-whitening (or skin-lightening) composition for external use containing an alcohol-extracted chia (Salvia hispanica) seed extract and to a method of whitening skin by topically applying a composition containing an effective amount the alcohol-extracted Salvia hispanica seed extract.
Skin color is primarily determined by the amount of melanin present in the skin. Melanin is a brown-black pigment present in the skin, which protects the body from the damaging effects of ultraviolet radiation. Due to the dark color of the pigment, lower amounts of melanin result in lighter skin color while higher amounts result in darker skin color. Melanin is formed by the oxidation of the amino acid tyrosine to dihydroxyphenalanine in melanocytes via a process termed melanogenesis. Within melanocytes, melanin is bound to a protein matrix to form melanosomes, where tyrosinase converts tyrosine to eumelanin (black pigment) or pheomelanin (yellowish and reddish pigment). Melanin biosynthesis involves a chain of oxidative reactions catalyzed by series of enzymes. In addition to tyrosinase, DOPAchrome tautomerase (TRP-2) and DHICA oxidase (TRP-1) are responsible for converting DOPAchrome to 5,6-dihydroxyindole-2-carboxy acid, which leads to the formation of eumelanin.
In some cases, it is desirable to reduce or inhibit melanogenesis, for example, to cause skin whitening or lightening, to eliminate “age spots”, lentigenes, or to reduce hyperactive melanocytes. Thus, in recent years, cosmetic compositions have been developed to reduce the amount of melanin in the skin and therefore, whiten the skin. These development efforts have focused on whitening agents that inhibit the function or activity of tyrosinase or block the chain reaction at various points in the melanogenesis pathway. Thus, compositions including these agents may achieve a skin whitening or lightening effect by blocking tyrosinase activity, reducing tyrosinase synthesis, inhibiting TRP-1 and/or TRP-2, blocking melanin transfer from melanocytes to keratinocytes, and/or accelerating the desquamation of the keratinocytes. Accordingly, whitening compositions have been developed that include hydroquinone, phenylthiourea, vitamin C and its derivatives, kojic acid, arbutin, various polyphenols, including flavonoids, such as flavones, flavonols, flavanoids, flavanols, isoflavonoids, chalcones, and catechin; linoleic acid, α-linolenic acid, glutathione, cysteine, endothelin antagonists, keratinocyte receptor inhibitors, placenta extract, and mulberry extract among others.
Despite the efficacy of the above compounds in producing whiter skin, alternatives that are effective and possess desirable attributes are continually being sought. Botanical source materials, including seeds, are known to carry or store a rich variety of nutritionally or medicinally beneficial bioactive agents, including antioxidants, fatty acids, vitamins, flavonoids, and other phytochemicals. In many cases, these bioactive agents include known whitening agents present in seed oil preparations. For example, conventional chia (Salvia hispanica) seed oil preparations are known to contain high levels of α-linolenic acid and linoleic acid, two fatty acids known to suppress melanin production (Ando et al., Arch. Dermatol. Res., 290:375-381, 1998). Fatty acids, such as α-linolenic acid and linoleic acid may be extracted from plant seed materials as oils produced by a number of different methods. These include expeller pressing methods employing mechanical pressure and friction, or may involve the use of chemical solvents, such as hexane or alcohol, in conjunction with various temperature, pressure, or distillation steps. A given extraction process may cause physical and chemical changes to the bioactive agents resulting in different biochemical profiles, however.
The inventors of the present application have unexpectedly found that an alcohol-extracted Salvia hispanica seed extract according to the present invention provides a dramatically increased efficacy in reducing total melanin content compared to compositions containing otherwise identical amounts of linoleic acid and/or α-linolenic acid alone.